Japan Isn't Appetizing Without Trade Pact

President Barack Obama and Japanese Prime Minister Shinzo Abe dined on sushi in Tokyo this week, which Mr. Obama declared to be the best he's ever had. But behind the scenes, their negotiators quarreled over rice and beef tariffs. Unless this food fight is resolved, investors in Japan could be left with indigestion.

At issue is the Trans-Pacific Partnership, a free-trade agreement among a dozen countries that would boost Japanese exports and open up its sclerotic domestic sectors such as agriculture and services. It is...